Just one of at least three sites in Pennsyvania where rocks "ring" when struck with a hammer or other similar type object is the most famous, Ringing Rocks State Park.
Located in Upper Black Eddie, not far from where Washington tossed his dollar accoss the Potamic is a ten feet deep seven acre boulder field, found in the middle of a small forrest. While it might seem to be out of place with its surroundings, what is most unusual are the rocks themselves. About thirty percent ring like a bell. Different tones for different rocks they have defied any real explanation as to why they do what they do! Made up of Diabase, just like all the other rocks in the field, the ringers ring wheather left in place, or taken to a lab for study. They ring wheather whole, or in pieces, with each subsequent piece ringing. "Rock concerts" have been performed in the past - with the earliest being by a Mr. Ott in 1890, and the latest taking place just recently as local musicians gathered to play them as a group using sticks, rocks, hammers, and other implements to play an concerto of sorts.
While rocks that ring are not a new phenomenon - the ancient Egyptians used basalt as a type of xylophone, they are made up of different materials from those found in Pennsylvania. Scientist have yet to come up for a real reason certain stones ring, while others of the same composition do not.
Stop on off at Ringing Stones State Park, and ring for yourself! And while you are there, try and figure out why there is no dirt accumulation in and on the rocks, no birds around them, and nothing save for a few spiders and snakes living in among them.